Re: [linux-usb-devel] 2.6.20-rc4: null pointer deref in khubd

[Alan Stern]

On Wed, 10 Jan 2007, Oliver Neukum wrote:

> Am Mittwoch, 10. Januar 2007 17:14 schrieb Alan Stern:
> > On Wed, 10 Jan 2007, Oliver Neukum wrote:
> > 
> > > Am Mittwoch, 10. Januar 2007 11:49 schrieb Pavel Machek:
> > > > usb 2-1: new full speed USB device using uhci_hcd and address 68
> > > > usb 2-1: USB disconnect, address 68
> > > > usb 2-1: unable to read config index 0 descriptor/start
> > > > usb 2-1: chopping to 0 config(s)
> > > 
> > > Does anybody know a legitimate reasons a device should have
> > > 0 configurations? Independent of the reason of this bug, should we disallow
> > > such devices and error out?
> > 
> > About the only reason to allow such devices is so that the user can run 
> > lsusb to try and get more information about the problem.  With no 
> > configurations, the device won't be useful for anything.
> 
> Regarding the bug this device uncovers, it seems to me that this in drivers/base/core.c
> 	if (parent)
> 		klist_add_tail(&dev->knode_parent, &parent->klist_children);
> should make knode_parent a valid node under all circumstances.
> Hm.

I haven't seen the original bug report.  Where does the NULL pointer deref 
occur?

Alan Stern

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